18 JOURNAL OF COSMETIC SCIENCE depending on the viscosity of the continuous phase, and that in turn depending on the concentration and/or molecular weight of the polymer used in the continuous phase. COLOR OF MOISTURE MASKS Results in Table II show that the L values of moisture masks containing 1% HEC and different concentrations of mucilage increased with increasing concentration of the mucilage used, whereas +a values decreased or even changed to -a values, and -b values increased or even changed to +b values with increasing concentration of the extract used in the moisture mask. Increases in the L values indicated that the moisture masks containing higher than 1.5% of mucilage were whiter than those containing 2% HEC + 5% humectant or 2% MC + 5% humectant. Decreases in +a values or changes to -a values with increasing concentration of the mucilages indicated that the moisture mask became more green and less red, whereas increases in -b values or changes to b+ values with increasing concentration of the mucilage indicated that the moisture mask became less blue and more yellow. This may be because the mucilage contains chlorophyll and some carotenoids (28). Therefore, with the increased concentration of mucliage used, the green and yellow color of the moisture mask increased. An increase in the green and yellow color of the moisture mask may appeal to consumers owing to the freshness and warmth of nature associated with these colors. EFFECTS ON WATER-HOLDING CAPACITY OF MOISTURE MASKS The efficacy of moisture masks in terms of water-holding capacity on the skin was tested by the corneometer method (25-27). The corneometer measures changes in electrical capacitance that are related to the moisture content of the stratum corneum before and after applying a moisture mask. Results in Figures 3 and 4 show that after applying moisture masks containing different types and concentrations of thickening agents of HEC, MC, or mucilage, the electrical capacitance increase ratio increased, then decreased progressively. This may be because after applying the moisture mask, the moisture content of the skin increased, and so the electrical capacitance increase ratio increased accordingly. As water evaporated over time, the electrical capacitance increase ratio decreased. After applying moisture masks containing 1% HEC and 0.5% to 2.0% mucilage for 60 min, electrical capacitance increase ratios were between 59% and 42% (Figure 3), whereas electrical capacitance increase ratios were between 59% and 45% for masks containing 2% HEC + 5% humectant or 2% MC + 5% humectant (Figure 4). The results indicate that the water-holding capacities of moisture masks containing different concentrations of mucilage were similar to those containing 2% thickening agents and 5 % humectants. This may be due to the molecular weight of mucilage being larger than that of humecant or due to the mucilage having good water-holding capacity. FILM-FORMATION TIME OF MOISTURE MASKS Results in Table III show that the film-formation times of moisture masks were in the order of moisture masks containing 1% extract + 1% MC 2% MC + 5% humectant 1% extract + 1% HEC 2% HEC + 5% humectant. However, for those moisture masks containing 1% HEC and different concentrations of mucilage, the film-formation

WATER-SOLUBLE MUCILAGE IN A MOISTURE MASK 19 times decreased from 12.05 min to 14.08 min with the increased concentration of mucilage used. This may be because film formation results from an aggregation of film-forming compounds, i.e., HEC, MC or mucilage, after the solvent evaporates (29). Therefore, film-formation time decreased with increasing concentration of film-forming agents. STORAGE STABILITY Results in Figure 5 show that the apparent viscosity of moisture masks containing 2% HEC + 5% humectant or 1% HEC + 1% mucilage was relatively stable within six weeks, and then decreased and leveled off at eight weeks. However, for moisture masks containing 2% MC + 5% humectant or 1% MC + 1% mucilage, the apparent viscosity started to decrease from the beginning, until the fourth or sixth week, and then leveled off. This may be attributed to different time courses of the coalescense of dispersed lipid droplets, and it resulted in the decreases in the apparent viscosity of moisture masks. The apparent viscosity of masks containing HEC was higher than that of those containing MC. The onset times of coalescense of dispersed lipids for those moisture masks con- taining HEC were later than for those containing MC. Therefore, the apparent viscosity of moisture masks containing MC decreased from the beginning of storage and then leveled off after six weeks. Although the apparent viscosity of moisture masks decreased during storage, no phase separation occurred. The moisture masks were stable for more than three months stored at 4øC. CONCLUSION Increasing concentration of water-soluble mucilage in moisture masks increased their water-holding capacity but decreased film-formation time. Moisture masks containing 1% water-soluble mucilage and 1% HEC have a higher water-holding capacity, al- though the apparent viscosity was lower than for those containing 2% MC and 5% humectant. ACKNOWLEDGEMENTS The authors express their gratitude to the National Science Council, Republic of China (Project No. NSC 88-2313-B-019-022) for its financial support. REFERENCES (1) S. Maeshige, Chemical studies on the green alga Monostroma nitidium Wittrock-I components sugar of the mucilage, Bull. Jap. Soc. Sci. Fish, 28, 326-334 (1962). (2) T. Kawabe, T. Nagaoka, G. Nagahama, H. Morita, and A. Ohbayashi, Generation of dimethyl sulfide from dimethyl-[3-propiothetin in an extract of green alga Monostroma nitidium and its retention by cyclodextrin, Agric. Biol. Chem., 53, 2587-2591 (1989). (3) S. Maeshige, Chemical studies on the green alga Monostroma nitidium Wittrock-II low molecular carbohydrate in the alga, Bull. Jap. Soc. Sd. Fish, 28, 606-609 (1962). (4) T.C. Lii, Physico-chemical properties of water-soluble polysaccharides of Monostroma nitidium. MS thesis, National Taiwan Ocean University (in Chinese) (1986).